1. Field of the Invention
This invention relates to the production of drip irrigation lines, and particularly to the production of such drip lines in which emitters are fixed in a conduit at spaced-apart locations.
2. Related Art
U.S. Pat. No. 3,981,452 of Eckstein describes a method of manufacturing a continuous drip irrigation line by inserting drip emitters into a continuous and uninterrupted conduit. These emitters are cylinders having an outer surface structured to cooperate with the enclosing conduit to form pressure-reducing passageways. This method was further extended by Mehoudar as is disclosed in U.S. Pat. No. 5,022,940 to provide for the insertion of emitters that take up less than the full periphery of the conduit. The emitters are inserted into the extruded conduit by means of a mechanical pusher that is electrically or pneumatically driven and electronically controlled. The pusher pushes each emitter through the cross head and then retreats.
The insertion speed of the pusher must be controlled so that as the emitter reaches the molten conduit coming out of the cross head, it has the same speed as the conduit. This prevents breaking or collapsing of the conduit and allows heat welding of the emitter to the conduit. Further, the pusher has to be withdrawn from the conduit to its start position before the next emitter can be inserted in the conduit. This reciprocating motion is a time consuming process and is limited to the mechanical capabilities of the pusher and associated controller and emitter feed mechanism.